Polymeric composites that contain organic and/or inorganic filler materials have become desirable for a variety of uses because of their excellent mechanical properties and weathering stability. In general, the superior properties of the polymeric composites are achieved through use of the polymer as the matrix material that acts as a glue with enhanced flexural properties or as a fibrous component providing reinforcement and improved tensile properties. The inorganic material imparts various properties of rigidity, toughness, hardness, optical appearance and interaction with electromagnetic radiation, density, and many other physical and chemical attributes. A proper blend of polymeric and inorganic materials provides for a composite with optimal properties at a desirably low cost.
Polyurethane composites composed of a polyurethane binder and fly ash filler with glass fiber reinforcement have been shown to be very useful. Specific uses of such composites include applications as interior and exterior cladding on buildings. However, one challenge for highly-filled filler-polyurethane composites is that it is very difficult to improve the mechanical performance of such materials without incurring significant costs. Another challenge is that there exists a threshold for the total content of the fly ash filler and reinforcement materials that can be incorporated into the composites. In particular, raising the content of fly ash filler and/or reinforcement materials can greatly increase the viscosity of the polyurethane mixture and eventually make such systems difficult to process and manufacture into gross and net shapes. There is a need to improve the properties of filled composites. The compositions and methods described herein address these and other needs.